ASSET RETIREMENT AND ENVIRONMENTAL REMEDIATION OBLIGATIONS - Summary (Details) - USD ($) $ in Thousands |
9 Months Ended | ||
|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Dec. 31, 2025 |
|
| Asset Retirement Obligation and Accrual for Environmental Loss Contingencies [Roll Forward] | |||
| Obligations at beginning of period | $ 336,768 | ||
| Liabilities settled | 41,384 | $ 8,912 | |
| Accretion expense | 2,839 | ||
| Change in estimate | 10,401 | ||
| Total obligations at end of period | 287,821 | ||
| Less current obligations at end of period | (119,979) | ||
| Long-term obligations at end of period | $ 167,842 | $ 200,267 | |